package com.hit.basmath.learn.others;

/**
 * 274. H-Index
 * <p>
 * Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index.
 * <p>
 * According to the definition of h-index on Wikipedia: "A scientist has index h if h of his/her N papers have at least h citations each, and the other N − h papers have no more than h citations each."
 * <p>
 * Example:
 * <p>
 * Input: citations = [3,0,6,1,5]
 * Output: 3
 * <p>
 * Explanation: [3,0,6,1,5] means the researcher has 5 papers in total and each of them had
 * received 3, 0, 6, 1, 5 citations respectively.
 * Since the researcher has 3 papers with at least 3 citations each and the remaining
 * two with no more than 3 citations each, her h-index is 3.
 * <p>
 * Note: If there are several possible values for h, the maximum one is taken as the h-index.
 */
public class _274 {
    public int hIndex(int[] citations) {
        int n = citations.length;
        int[] buckets = new int[n + 1];
        for (int c : citations) {
            if (c >= n) {
                buckets[n]++;
            } else {
                buckets[c]++;
            }
        }
        int count = 0;
        for (int i = n; i >= 0; i--) {
            count += buckets[i];
            if (count >= i) {
                return i;
            }
        }
        return 0;
    }
}
